All APS inverter/charger models automatically switch between AC (utility power) and DC (battery power) sources to provide continuous support for connected equipment. Different models feature different transfer times when switching between AC and DC power sources. Select APS models switch in as little as one half cycle (10 ms). Their fast transfer switching makes them ideal for supporting all applications, but particularly sensitive computer and telecom equipment. All other models provide standard one cycle (20 ms), switching.